Using SHA1 in C

I am developing a tool in C which takes in a file as a input. I need to compute the SHA1 sum for the file. This tool needs to be platform compatible with Linux, Mac and开发者_如何学编程 windows. The files are huge in size ranging from 150MB to 2G. I need the tool to be able to compute the SHA at least as fast as the sha1sum Linux utility.

Any suggestions how I could go about incorporating SHA1? I am wary about using the openssl interface, since the clients for the tool would not necessary have openssl installed.

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OpenSSL is the de facto standard in C. It needn't be installed since you can supply the library along with your program (or even statically compile it).

OpenSSL is BSD-style licensed, so you can even use just their SHA1 code directly in your program (giving credit), though it may be tricky to decouple it from the library.

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My digest package for R includes short standalone C sources for md5, sha1, sha256, ... which were written by Christophe Devine. It is nice code, and it includes a few tests replicating the reference results from the specifications.

I believe his site no longer exists, but when I eg checked Google Code Search for it, the same functions seem to have been included in a number of other open source projects. You can easily extract these sources from my tarballs or even directly from the SVN directory at R-Forge's digest repo.